System of electrical distribution.



Patented Aug. 5, I902.

C. P. STEINMETZ.

SYSTEM OF ELECTRICAL DISTRIBUTION.

(Application filed June 30, 1900.)

(No Model.)

r f 3% n m mm mm P m I a h C Witnesses Httg.

NORRIS wrrzns co worn L UNITED STATES PATENT OEEIcE.

CHAR-LES P. STEINMETZ, OF SOHENEOTADY, NEIV YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NETV YORK.

SYSTEM OF ELECTRICAL DIESTRIBUTEON.

SPECIFICATION forming part of Letters Patent No. 706,123, dated August 5, 1902.

Application filed June 80, 1900. Serial No. 22.133- (No model.)

To a whom/ it nuty concern:

Be it known that I, CHARLES P. STEINMETZ, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Systems of Electrical Distribution, (Case No. 1,456,) of which the following is a specification.

Constant-current circuits feeding arc-lights or the like are frequently supplied with current through rectifiers connected to suitable sources of alternating current. In stations employing systems of this character it is usual to find a number of rectifiers each fed from a separate source of constant current such, for example, as a constant current transformer either of the three-phase or quarter-phase type. This arrangement involves the inconvenience of operating a considerable number of transformers, the increased expense of the apparatus, a larger floorspace, decreased efficiency, &c. I have found that these and other objections as well may be obviated by making use of one large source of constant current to supply current for all of the rectifiers of the station, or at least a group of rectifiers, and to feed each individual rectifier from the secondary of a transformer the primary winding of which is in series with the primary windings of the companion transformers and in circuit with the source of constant. current.

My invention, both as to its construction and mode of operation as well as to certain adaptations of the same, will be better un derstood by reference to the following; description, taken in connection with the accompanying drawing.

The drawing represents a system embodying the characteristics above mentioned and including certain modifications whereby the cost of the apparatus is much reduced and the power factor largely increased.

Oonstant-potential-supply mains are indicated at 1 2, and across these mains is connected the primary 3 of a transformer of the constant-potential type, having a secondary winding 4:, from points in the length of which extend taps 5. A switch-arm 6 or other appropriate contact-making device is adapted to make connection with any one of the taps '5. The secondary at is connected in series with the secondary winding 7 of a constantcurrent transformer, the primary winding 8 of which is connected across the mains l 2. This transformer is of the well-known type having relatively movable primary and secondary windings, and its construction and mode of operation being well understood in the art no further explanation of the same is necessary here. It is to be understood, however, that instead of an automatic constantcurrent-regulating device of this character I may employ any other automatic regulating device performing substantially the same function. Thus instead of the constant-cur rent transformer I may employ a constantcurrent reactive coil, which, as is well known, differs from the transformer only in that the two windings are connected into series with each other and with the circuit to be regulated. The constant-current circuit, including the two secondaries 4E 7,leads to and passes through a plurality of transformers 9 to 14 of the constant-potential type. Some of these transformers are arranged so as to feed rectifiers, while others are used for supplying current to a synchronous motor or motors for driving the rectifiers. Thus, for example, the secondaries 15 and 16 are appropriately connected to rectifying-commutators 17 1S, respectively, while the secondaries 19 20 are similarly connected to the rectifiers 21 and 22. The secondary 23 of the transformer 9 supplies current to the synchronous 'motor 24, while in a similar manner the secondary 25 of the transformer 14 supplies current to the synchronous motor 26. Instead, however, of dividing up the rectifiers into groups and operating each group from a separate synchronous motor I may of course drive all of the rectifiers from a single synchronous motor. Whatever be the number of synchronous motors employed, it is to be understood that their fields are to be excited by direct current obtainedfromanysuitablesource. Inthe drawing I have merely indicated direct-current leads 27 28 for conveying the field-exciting current to the motors.

In the operation of the apparatus described the constant current in the main supply-circuit is obtained. by the conjoint regulating action of the two transformers whose secondaries 4E and 7 are in series with each other, as shown. For large variations in load the regluating-switch 6 is moved so as to bring the current within an approximation of constancy,whereupon the constant-current transformer comes into operation and by means of relative motion between its primary and secondary windings S '7 automatically brings the current to its normal value. The switch-arm 6 may be operated byan attendant and should be moved so that the movable coil or coils of the constan t-current-regulatin g device should be brought to some intermediate position in theirregulatingstrokeorstrokes. Automatic regulation for the smaller variations from normal current will be then taken care of by the constant-current device.

The system thus described possesses many advantages, among which is that of steadier operation, since each individual lamp or even circuit is a lesser part of the system than is the case where each circuit is fed from its own source of supply. Furthermore, the synchronous motor or motors being operated by the total current of the system will be less liable to hunt, due to the greater steadiness of this current, thereby avoiding serious difficnlties with the commntating action of the rectifiers.

It is obvious that my invention is capable of many modifications and adaptations, and I wish the same to be included within the scope of my claims. Moreover, although I have shown my invention as embodied in a singlephase system I have done so merely for convenience of illustration, since it maybe, and, indeed, generally is, used in connection with a multiphase system.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. The combination of a source of current of substantially constant value, a plurality of rectifier-s, and means for supplying said rectifiers with current from said source.

2. The combination of a source of current of substantially constant value, a plurality of rectifiers,andmeansforderivingcurrent from said source inductively and supplying it to said rectifiers.

3. The combination of a source of constant current, a synchronous motor, a rectifyingcommutator driven thereby, and means for starting and supplying both the synchronous motor and the rectifying-commutator with current derived from said source.

4. The combination of a constant-current circuit carrying alternating current, a plurality of transformers having windings in series therewith, and rectifying-commutat0rs fed from said transformers.

5. The combination of a constant-current circuit, and a plurality of rectifying-commutators supplied with current thereby.

6. Thecombinationofatransformerhaving a divided secondary, a constant-current-regulating device in series with said secondary, and a consumption-circuit fed by said secondary and regulating device.

7. The combination of a plurality ofsources of variable alternating electromotive force in series, and rectifying devices fed from said sources.

8. The combination of a constant-current circuit, a plurality of transformers having windings in series with said circuit, and rectifying-commutators fed from other windings on said transformers.

9. The combination of a constant-current circuit,means for deriving otherconstant-current circuits therefrom, and means for rectifying current flowingin the constant-current circuits last mentioned.

10. The combination of constant-potential mains, a transformer havingits primary connected across said mains, a constant-current circuit including the secondary of said transformer, and means for varyingthe number of active turns of said secondary.

In witness whereof I have hereunto set my hand this 29th day of June, 1900.

CHARLES P. STEINMETZ.

lVitnesses:

BENJAMIN 13. IIULL, MABEL E. JAooBsoN. 

